1. Field of the Invention
The present invention relates to a method of and apparatus for cleaning objects to be treated, such as semiconductor wafers or LCD (liquid crystal display) substrates etc., by immersing them in a cleaning liquid such as a chemical or a rinse, and sequentially drying the objects cleaned.
2. Description of the Related Art
During the process of fabricating a semiconductor device, a cleaning method is widely used to sequentially immerse objects to be treated or processed, such as semiconductor wafers or glass LCD substrates, into a processing tank filled with a processing liquid such as a chemical or rinse (cleaning liquid), to wash them.
A cleaning and drying apparatus of this type is provided with a drying device wherein a drying gas obtained from vapor of a volatile organic solvent such as isopropyl alcohol (IPA) is brought into contact with the surfaces of the wafers after the cleaning, the vapor of the drying gas condenses thereon or adheres thereto, and thus moisture on the wafers is removed, drying the wafers.
A conventional cleaning and drying apparatus that is known in the art as a typical example of this type of cleaning and drying apparatus is shown in FIG. 27. It comprises a cleaning tank A (cleaning chamber) which is filled with a chemical such as hydrofluoric acid and a rinse (cleaning liquid) such as distilled water, wherein objects to be treated, such as semiconductor wafers, are immersed in the chemical and cleaning liquid therein; a drying portion B positioned above the cleaning tank A; and a movement means such as a wafer boat C that holds a plurality of wafers W, such as 59 wafers W, and moves those wafers W into the cleaning tank a and the drying portion B.
Within the cleaning and drying apparatus of the above configuration, supply nozzles D that are connected selectively to a chemical source and a cleaning liquid source (not shown in the figure) are disposed within the cleaning tank A; drying gas supply nozzles E that are connected to a source (not shown in the figure) of a gas mixture of a drying gas such as IPA and nitrogen (N2) are disposed within the drying portion B; an aperture G that is freely enterable by a wafer conveyor chuck E is provided in an upper portion of the drying portion B; and a lid H is provided for opening and closing the aperture G.
In the thus-configured cleaning and drying apparatus, a plurality of wafers W, such as 50 wafers W, that have been transferred into the drying portion B by the wafer conveyor chuck E are received by the wafer boat C which is on standby within the drying portion B, the wafer boat C that has received these wafers W is lowered into the cleaning tank A to move the wafers W thereinto, and chemical processing is performed by supplying a chemical thereto and cleaning is performed by supplying a cleaning liquid thereto until it overflows. After the chemical processing and cleaning have been completed, the wafer boat C rises to move the wafers W into the drying portion B, and a drying gas (IPA+N2) is supplied from the drying gas supply nozzles E to bring the drying gas into contact with the wafers W, thus drying them. The dried wafers W are taken by the wafer conveyor chuck E that enters into the drying portion B and are conveyed outside, whereby one cycle of cleaning and drying is performed.
However, when the wafers W are transferred between the wafer boat C and the wafer conveyor chuck E that enters the drying portion B in the conventional cleaning and drying apparatus of this type, it is necessary to move the chuck portions sideways in order to enable the wafer conveyor chuck E to switch from a wafer holding state to a wafer non-holding state. It is therefore necessary to provide movement space within the drying portion B for the wafer conveyor chuck E, and the volume of the drying portion B must be increased accordingly. This increase in volume of the drying portion B not only leads to an increase in size of the apparatus, it raises further problems such as an increase in the amount of drying gas consumed therein and a lowering of the drying efficiency.
In addition, after the wafer boat C has risen to move the wafers W into the drying portion B of the above cleaning and drying apparatus, and during the drying process of supplying the drying gas to cause the drying gas to come into contact with the wafers W, the portions of the wafers W in contact with the wafer boat C that have been raised from within the cleaning liquid are in a state wherein drainage therefrom is bad and it is also difficult for the drying gas to come into contact therewith. Therefore, considerable time is required to dry the portions of the wafers W in contact with the wafer boat C, which causes a further increase in the consumption of drying gas, and this raises problems concerning decreased drying efficiency and increased cost. There are further problems concerning the danger of unevenness in the drying and reductions in yield.
A first objective of the present invention is to provide a cleaning and drying apparatus which can be designed to have a drying chamber with a small volume so that the entire apparatus is more compact, wherein a reduction in the consumption of drying gas and an increase in the drying efficiency can be expected.
A second objective of the present invention is to provide a cleaning and drying apparatus and method which can be expected to solve the problem of bad drainage at held portions, provide good contact between those portions and the drying gas, shorten the drying time and reduce the consumption of drying gas, improve the drying efficiency and the yield, and also reduce costs.
In order to achieve the first objective, a first aspect of the present invention relates to a cleaning and drying apparatus having a cleaning chamber for cleaning an object and a drying chamber positioned above the cleaning chamber for drying the object, the apparatus including: an enclosure defining the drying chamber, the enclosure including first and second enclosing elements capable of relative movement, such that the enclosing elements are capable of adopting an engaged state and a separated state concomitant with the relative movement, wherein when the enclosing elements are in the separated state the first and second enclosing elements are spaced apart horizontally and the object is allowed to be transferred into and out of the drying chamber between the enclosing elements.
In order to achieve the second objective, a second aspect of the present invention relates to a cleaning and drying apparatus having a cleaning chamber for cleaning an object and a drying chamber positioned above the cleaning chamber for drying the object, the apparatus including: carrying means for carrying the object movable between the cleaning chamber and the drying chamber, the carrying means being in contact with a first portion of the object when the carrying means carries the object; and holding means provided in the drying chamber for holding the object in a second portion thereof, the second portion being different from the first portion.
In order to achieve the second objective, a third aspect of the present invention relates to a method of cleaning and drying an object, including the steps of: (a) accommodating the object in a cleaning chamber in a state in which a first portion of the object is in contact with carrying means, and cleaning the object by a cleaning liquid supplied into the cleaning chamber; (b) raising the carrying to move the object into a drying chamber provided above the cleaning chamber; (c) holding a second portion of the object that differs from the first portion by holding means, and making the carrying means be away from the object; and (d) drying the object with a drying gas, in a state in which the second portion of the object is held by the holding means.
The advantages and features of the present invention will be discussed in detail below, with reference to the accompanying figures.